The present invention relates generally to the field of machines for energy conversion, such as motors and generators. Motors convert electricity into mechanical energy. Generators generate electricity by converting mechanical energy into electrical energy. A prime mover, such as an engine driving a rotating shaft, provides the mechanical energy. A rotor having permanent magnets or electromagnets rotates with the rotating shaft, generating a magnetic field that causes electricity to be generated in a stationary stator.
Superconducting electrical machines, such as a superconducting generator, use the principle of superconductivity to significantly reduce the electrical resistance in the conductors of the generator. Superconductivity requires maintaining the conductors at very low temperatures. The extreme cold temperatures require operation in a vacuum to prevent icing and minimize heat transfer by convection. Often, complex vacuum pumping and sealing systems are required to maintain the conductors at the very low temperatures necessary for superconductivity. The containment apparatus used to reach and maintain superconducting temperatures is called a cryostat.